18 THE DESCENT OF THE PRIMATES 



differ from all other Mammals, namely, the pos- 

 session of a diminutive yolk-sac which never 

 entirely fills the cavity of the embryonic vesicle.^ 

 This latter point, which I am not going to elu- 

 cidate any further either, is of all the more 

 importance as it must keep pace with special 

 differences of primary importance in the develop- 

 ment of the germlayers. 



'And so henceforth we are obliged to range 

 Tarsius with man and monkeys in one order 

 which may retain Linnaeus' adequate name of 

 Primates. We must at the same time recognize 

 that the facts here alluded to render it highly 

 improbable that many of the most important 

 characteristics of the Primates could ever have 

 been derived from arrangements such as we find 

 them in the Lemurs; so that the designation of 

 the latter order by the well-known name of 

 Prosimise is worse than misleading, because dis- 

 tinctly false. J 



A delicate question has yet to be solved with 

 respect to the fossil genus Anaptomorphus, — 

 delicate in so far as I can understand your 

 smiling at the idea that I could give you any 

 details of the foetal development of a small 



1 A. A. W. Hubrecht, Die Keimblase vou Tarsius. Fest- 

 schrift fiir Gegenbaur, Leipzig, 1896, 



